1. Field of the Invention
The present invention relates to a so-called ink jet recording apparatus that discharges ink liquid from its orifices and causes it to adhere to a recording medium for the formation of images thereon. More particularly, the invention relates to an ink liquid fixing device for accelerating the fixation of the ink liquid that has adhered to a recording medium, and also, to an ink jet recording apparatus provided with such ink liquid fixing device.
2. Related Background Art
In recent years, there has been developed an ink jet recording apparatus that discharges ink (recording liquid) from its orifices (ink discharge ports) as liquid droplets and causes them to adhere to a recording medium (recording paper) for the formation of images thereon. This apparatus is not only capable of printing at high speeds at low costs, but also, capable of recording (printing) on an ordinary paper, besides such an advantage that the apparatus is easily made usable for the formation of images in colors. With these features and advantages, the future prosperity thereof is anticipated more than ever.
Ink absorption is slow when recording on an ordinary paper as compared to recording on a paper specially treated for a good ink absorption. The ink fixation should be accelerated by giving heat to such an ordinary recording paper. Particularly when images are recorded in colors, the amount of ink to be used is much greater than that of ink to be used for a monochromic recording. It is only natural that more time is required for the completion of the fixation. As a result, the acceleration of ink fixation is extremely important to make the time required for recording operation shorter by giving heat to the recording paper to accelerate the fixation of prints on it.
In general, therefore, it has been practiced to appropriately select for use either one of a hot plate heating method wherein a recording paper is in contact with a hot plate; a hot air heating method wherein hot air is blasted onto recording liquid; and a radiant heat method wherein a recording paper is heated by the application of radiant heat using an infrared heater.
Also, as an ink fixing apparatus, there is the one in which the hot air heating method and the radiant heat method are combined for use as disclosed in U.S. Pat. No. 5,020,244. However, this apparatus is designed to reduce the energy to be given to heating elements by circulating most of the hot air in the circulating path around the position of such heating elements and the feeding path of the recording paper. As a result, along the fixation of ink liquid, the moisture contained in the circulating hot air becomes only higher increasingly. Therefore, dew condensation takes place in the ink fixing apparatus after it has been used for a long time. There is thus a possibility that electrical components are damaged, and that dew droplets fall off to the surface of the paper after recording, and stain the recorded images, among other disadvantages.
The hot plate heating method in which a recording paper is in contact with a hot plate may scorch the recording paper if the temperature of the hot plate is too high. Therefore, it is difficult for this method to give heat to the paper rapidly. Hence the time required for the fixation cannot be made shorter. In addition, there is a problem that uneven fixation often ensues because of the unstable contact between the hot plate and the recording paper.
The hot air heating method in which hot air is blasted onto a recording paper requires a measure for the diffusion of vapor contained in the hot air in order to prevent dew condensation. Also, a large electric power is inevitably required to obtain a sufficient accelerating effect of fixation, leading to extremely high costs.
The radiant heat method using an infrared heater makes it difficult to appropriately control the quantity of heat generated by the infrared heater. If the quantity of heat given to a recording paper is too large, scorching takes place. If it is too small, the fixation becomes insufficient. Also, there is a disadvantage that cooling means should be provided for the infrared heater itself in order to prevent its overheating.
In consideration of the problems encountered in the conventional techniques described above, the present invention is designed. It is an object of the invention to provide an ink liquid fixing device and an ink jet recording apparatus, capable of fixing ink rapidly at lower running costs without any fear of scorching to occur on a recording paper or any fear of uneven fixation and dew condensation to be generated.
It is another object of the invention to provide an ink liquid fixing device and an ink jet recording apparatus, having heating means arranged therefor to heat a recording paper being fed along a given feeding path, such heating means comprising:
a heat generating element arranged to face the recording paper; and
means for generating hot air by causing the atmosphere around the heat generating element to flow forcibly, and then, exhausting forcibly the hot air thus generated rapidly.
It is still another object of the invention to provide an ink liquid fixing device and an ink jet recording apparatus, capable of fixing ink on a recording paper evenly in a short period of time by heating the recording paper by use of both radiant heat and hot air for the effective utilization of energy of the heat generating elements to carry out an extremely rapid heating of the recording paper, and also, capable of preventing the surrounding devices from being contaminated due to the formation of any dew condensation by rapidly exhausting the hot air blasted onto the recording paper.
It is a further object of the invention to provide an ink liquid fixing device used for an ink jet recording apparatus that discharges ink liquid onto a recording medium arranged on a given feeding path for the formation of images on such recording medium, the fixing apparatus including the following:
a housing;
a first aperture for inducing air into the housing;
a second aperture having the width of the aperture wider than that of the recording medium arranged on the feeding path, this second aperture being arranged to face the recording surface of the recording medium arranged on the feeding path with given gaps formed between them on the upstream and downstream sides, respectively, in the feeding direction of the recording medium;
a heat emitting source facing the recording surface of the recording medium arranged on the feeding path through the second aperture;
side portions arranged on the circumference of the heat emitting source, with the first aperture being arranged on one end thereof, and the second aperture on the other end thereof; and
exhaust means for inducing the air outside the housing into the housing through the first aperture to guide the air to the recording surface of the recording medium arranged on the feeding path by way of the heat emitting source and the second aperture, and exhausting the air outside the housing by forming the air flow through the aforesaid gaps toward the upstream and downstream sides in the feeding direction of the recording medium.
It is still a further object of the invention to provide an ink jet recording apparatus that records by discharging ink liquid onto a recording medium for the formation of images on the recording medium arranged on a given feeding path, including the following:
a head holding unit for an ink jet head to discharge ink liquid; and
an ink liquid fixing device arranged on the downstream side of the head holding unit in the feeding direction of the recording medium, this ink liquid fixing device comprising:
a housing;
a first aperture for inducing air into the housing;
a second aperture having the width of the aperture wider than that of the recording medium arranged on the feeding path, this second aperture being arranged to face the recording surface of the recording medium arranged on the feeding path with given gaps formed between them on the upstream and downstream sides, respectively, in the feeding direction of the recording medium;
a heat emitting source facing the recording surface of the recording medium arranged on the feeding path through the second aperture;
side portions arranged on the circumference of the heat emitting source, with the first aperture being arranged on one end thereof, and the second aperture on the other end thereof; and
exhaust means for inducing the air outside the housing into the housing through the first aperture to guide it to the recording surface of the recording medium arranged on the feeding path by way of the heat emitting source and the second aperture, and exhausting it outside the housing by forming the air flow through the aforesaid gaps toward the upstream and downstream sides in the feeding direction of the recording medium.